ATP

Question 1

movement and energy
- how does myosin cause the power stroke
- what can the demand for ATP hydrolysis during strenous exercise
- which metabolic pathways are used to resynthesise ATP

Answer 1

• converts free energy change of ATP hydrolysis to kinetic energy
• as high as 12 hexillion molecules of ATP per minute (12 x 10(23)) or 1kg of ATP per minute
• varies for different types of exercise

Question 2

ATP-ADP cycle-
- what happens when ATP is hydrolysed
- link between anabolism and catabolism

Answer 2

• Chemical energy is released from ATP when it is hydrolysed, losing a phosphate group (-6.3Kcal/mol)
• energy released from ATP breakdown is used to perform cellular work
  energy released from catabolism of other molecules (eg. PC) can be used to synthesise ATP

Question 3

Myokinase regulation of ATP
- how does it create ATP
- what makes the reaction more favourable
- when is it used
- max rate of ATP resynthesis

Answer 3

• combining/rearranging two ADP molecules creating ATP
• reduced ATP and increased ADP and AMP
• anaerobic and used during hard exercise
• 0.9 mmol/kg/sec

Question 4

how much ATP is needed during max exercise

Answer 4

3 mmol/kg/sec

Question 5

phosphocreatine (PCr) system in muscle-
- what is PCr
- how does it form ATP
- when is it used
- where is the enzyme that breaks down PCr located
- drawback of the system
- max rate of ATP resynthesis

Answer 5

• creatine with a phosphate attached
• PCr broken down by creatine kinase and phosphate and energy used to create ATP from ADP
• during hard exercise
• on the m-line, near myosin heads providing ATP needed at that site
• the resynthesis of PCr stores is slower than ATP (only last 7 secs during max exercise) so is not sustainable
• 2.6 mmol/kg/s

Question 6

what is resting level of ATP and what level will it not drop below during exercise

Answer 6

• resting ATP conc is ≈ 8 mmol/kg
• will not drop below 60% of resting levels due to enzymes myokinase and creatine kinase

Question 7

3 main energy-generating pathways (ATP turnover and how long)

Answer 7

• Phosphagen - very high ATP turnover, very short term (10 seconds predominant)
• Glycolytic - moderate ATP turnover, short term (10 secs to 50 seconds its predominant)
• Mitochondrial respiration - lowest ATP turnover, long term, 50 seconds plus